unit 9 – reaction rates and equilibrium
DESCRIPTION
Unit 9 – Reaction Rates and Equilibrium. The area of chemistry that concerns reaction rates (how fast a reaction occurs). Collision Model. Key Idea: Molecules must collide to react . However, only a small fraction of collisions produces a reaction. Why?. Not all “swings” are successful. . - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/1.jpg)
Unit 9 – Reaction Rates and Equilibrium
The area of chemistry that concerns reaction rates (how fast a reaction occurs)
![Page 2: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/2.jpg)
Collision ModelKey Idea: Molecules must collide to react.
However, only a small fraction of collisions produces a reaction. Why?
![Page 3: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/3.jpg)
Not all “swings” are successful.
![Page 4: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/4.jpg)
Why is it not burning?•Activation energy must be supplied (in the form of friction between friction strip and match tip)
![Page 5: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/5.jpg)
Collision ModelCollisions must have sufficient energy to produce the reaction
Must equal or exceed the activation energy.
1.
![Page 6: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/6.jpg)
Activation energy
A = Energy of reactants
D = Energy of products
B = Activation
energy(Highest Point) C =
Energy released by
reaction
![Page 7: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/7.jpg)
Collision ModelColliding particles must be correctly oriented to one another in order to produce a reaction.
![Page 8: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/8.jpg)
HCl with C2H4
![Page 9: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/9.jpg)
Reaction rate•A change in concentration of a reactant or product over time • In other words, speed a chemical reaction occurs
![Page 10: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/10.jpg)
Factors Affecting Rate1. Temperature As temperature INCREASES , reaction rate INCREASES. Because…
Particles collide more FREQUENTLY
Particles collide more ENERGETICALLY
2. Surface area as the surface area INCREASES, reaction rate INCREASES.
3. Concentration As the concentration INCREASES, reaction rate USUALLY INCREASES.
4. Presence of Catalysts, which lower the activation energy by providing alternate pathways
![Page 11: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/11.jpg)
Collision ModelRemember…Collisions must have sufficient energy AND a correct orientation to produce a reaction
Increasing temp, concentration, or particle size contributes to more energy and/or more chances at colliding with a correct orientation
1.
![Page 12: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/12.jpg)
Effect of temperature – more chances of successful collision
![Page 13: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/13.jpg)
Effect of surface area – More chances of successful collision
![Page 14: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/14.jpg)
Effect of concentration – More chances of successful collisions
![Page 15: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/15.jpg)
CATALYST
•A substance that speeds up a reaction without being consumed
![Page 16: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/16.jpg)
Lowering of Activation Energy by a Catalyst
* You don’t get more product, you just get it faster
![Page 17: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/17.jpg)
Catalysis•Enzymes: A large molecule (usually a protein) that catalyzes biological reactions• Example: Digestion• Substrate (s) ------------------- > product(s)
![Page 18: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/18.jpg)
Catalysis•Heterogeneous catalyst: Present in a different phase than the reacting molecules.
•Example: Catalytic converters in automobiles
•NO (g) N2 + O2
•CO (g) CO2
•Fuel + O2 CO2 + H2O
* Rh, Pt, metal oxides
***
![Page 19: Unit 9 – Reaction Rates and Equilibrium](https://reader035.vdocuments.site/reader035/viewer/2022062521/568161d4550346895dd1d4b6/html5/thumbnails/19.jpg)
Catalysis•Homogeneous catalyst: Present in the same phase as the reacting molecules.
•Example: “Elephant’s Toothpaste”
•2 H2O2 (aq) ---- > 2 H2O (l) + O2 (g)
•Intermediate steps: • H2O2(aq) + I-(aq) → OI-(aq) + H2O(l)• H2O2(aq) + OI-(aq) → I-(aq) + H2O(l) + O2(g)• I- is not consumed in the reaction.
KI